A Ducted Fan Vertical Take Off and Landing Unmanned Aerial Vehicle (UAV) is an aircraft utilized primarily for reconnaissance and surveillance by the U.S. military. The UAV typically is gasoline powered and employs a bladder-like fuel tank to store fuel on board. The bladder collapses during flight when fuel is drawn by the gasoline engine to ensure a consistent flow of gasoline to the engine regardless of the roll, pitch, or yaw of the air vehicle. The bladder requires that all air and residual fuel be evacuated prior to refueling to minimize the air and maximize the fuel volume. The UAV system employs a manual process which includes a syringe-like device to de-fuel and refuel the bladder of the UAV. The manual fueling process, however, is operator intensive and prone to errors. For example, the manual fueling method takes a significant amount of time, multiple repetitive steps and operator diligence to effectively and correctly fuel the UAV.
The process for fueling is to first remove all air and residual fuel by evacuating the flexible bladder. Evacuation of the bladder using a manual syringe requires (1) closing the clip of the syringe leading to the fuel canister and opening the clip leading to the aerial vehicle, (2) extracting residual fuel and air into the syringe, (3) closing the clip to the aerial vehicle and reopening the clip leading to the fuel canister, (4) pushing excess fuel and air into the fuel canister, and (5) repeating steps 1-4 until all fuel and air is extracted from the aerial vehicle. The bladder is then re-filled with a measured quantity of fuel. This is accomplished by (1) using the syringe to extract a measured amount of fuel from the fuel canister, (2) pushing excess air in the syringe back into the fuel canister before pushing fuel into the aerial vehicle, (3) closing the clip leading to the fuel canister and opening the clip leading to the aerial vehicle, (4) pushing fuel from the syringe into the aerial vehicle, (5) repeating steps 1-4 four more times, and (6) detaching the fuel line from the syringe to the aerial vehicle. Both the removal of air/residual fuel and the quantity of fuel delivered by the fueling process are critical. If either task is not properly performed this may result in a loss of the UAV during operation.